DE 102009033219 A1 shows a method and a device for determining a road profile of a traffic lane, said road profile extending in front of a vehicle in the direction of motion thereof. A road height profile of the traffic lane is determined by means of an image acquisition device or from vehicle proper-motion data, said traffic lane extending in front of the vehicle in the direction of motion thereof, wherein the image acquisition device may be a stationary camera that is arranged in the front section of the vehicle and comprises two image acquisition units. Active chassis control or damping may be controlled depending on the determined road height profile.
In driver assistance systems, the avoidance of accidents is getting more and more important. In particular, emergency braking systems make an important contribution to the avoidance of accidents. However, the effect of emergency braking systems decisively depends on the coefficient of friction of the ground with respect to the tire of the vehicle. In particular, the coefficient of friction of a wet pavement is considerably lower than that of a dry pavement.
WO 2011/007015 A1 shows a laser-based method for coefficient-of-friction classification in motor vehicles. To this end, signals of a lidar sensor/CV sensor directed toward the pavement surface are analyzed. After that, a coefficient of friction is assigned, particularly on the basis of the amplitude of the measured pavement surface. For example, one can estimate whether snow, asphalt or ice form the pavement surface.
It is obvious that prior-art methods for detecting the condition of a pavement surface are disadvantageous since either image acquisition and analysis is exclusively employed for chassis control or expensive lidar sensors that must be directed toward the pavement are required so that one might not be able to assess the condition of the pavement surface early enough.